Study On The Inhibitory Effect Of Plant Extract And Volatile Oil On 1 - Deoxy - D - Xylulose - 5 - Phosphorylated Isomerase (DXR)

Antibiotics are mainly microbial secondary metabolites or their synthetic mimics which are widely used for infectious diseases in clinic and administration of which dramatically decreases the mortality of infectious diseases. However, the drug-resistance of pathogens is becoming increasingly serious due to the abuse of antibiotics which will lead to the death of drug-sensitive microorganism and accumulation of drug-insensitive microorganism. Therefore, screening for novel safe and effective antibiotics aiming at new targets is very essential.Terpenoids with unique bioactivity are widely spread in nature.At the end of last century, a novel terpenoid biosynthetic pathway-MEP pathway-was found which exists in pathogens but not human. DXR, which plays the role of a rate-limiting enzyme in MEP pathway, is considered to be the most excellent target for screening new antibiotics.According to previous study, many plants extracts (PEs) and essential oils (EOs) show antibacterial activity. In this study, the inhibitory activities of 22 PEs and 39 EOs against E.coli DXR (EcDXR) of all the PEs and EOs was detected. Among PEs, the ethyl acetate extract (29.86%) and water extract (52.29%) of pomegranate seeds, ethyl acetate extract (32.01%) of banana peels, petroleum extract (41.43%) and n-butyl extract (29.03%) of green walnut peels, water extract of grape peels (39.02%), lotus seedpod (41.07%) and green tangerine (68.23%) showed relatively favourable inhibitory activity against EcDXR (final concentrations of the PEs were 1.0 mg/mL). Among all the EOs, the oil of peel of grapefruit (84.40%), catmint (73.14%) and wild peper (65.30%) demonstrate pretty promising activity (final concentrations of the EOs were 1.0 mg/mL). As to the fractions of catmint oil, the 7th fraction (petroleum ether:ethyl acetate=20:1,51.24%),28th fraction (petroleum ether:ethyl acetate=10:1,75.42%) and 30th fraction (methyl,58.81%) may contribute most to its whole inhibitory activity. We also brought up one hypothesis that polarer compounds had better inhibitory activity against DXR.